code: def assert_all_NAs(h2oframe, col_names):
      """
      Throw an assert error if not all columns of h2oframe with column names specified in list col_names are NAs.
  
      :param h2oframe:
      :param col_names:
      """
      for column_name in col_names:
          assert h2oframe[
              column_name
          ].all(), "H2O group_by() command is not working."
  
file_path: h2o-3/h2o-py/tests/testdir_munging/pyunit_groupby_allOps.py
imports: import sys
  import h2o
  import math
  from tests import pyunit_utils
  from h2o.utils.typechecks import assert_is_type
  from h2o.frame import H2OFrame
label_desc: Use image node_id 2 for calling a global function with example usage: assert_all_NAs(h2oframe, col_names) without return types